This invention relates to a method for manufacturing needle attached sutures and an apparatus therefor, in which the end of a needle used for surgical operations and the like is swaged in a state that the lead end of a suture is inserted in an insertion hole formed in the end of the needle to combine the needle with the suture together.
Recently, in the field of medical industry, there have been marketed sterilized needle attached sutures for surgical operations in which the lead end of a suture is fixedly attached to a needle. There have generally been known apparatuses for manufacturing such needle attached sutures comprising a needle retaining unit for retaining a needle in a certain direction, and a swaging device for fixedly swaging the end of the needle with the lead end of a suture inserted in an insertion hole formed in the end (disclosed in, e.g., Japanese Examined Patent Publication No. HEI 4-66579).
The prior art apparatus mentioned above has been involved with the following problems to overcome.
In producing such needle attached sutures, a strength for combining the end of a needle with a suture (swaging strength) is an essential matter for the following reasons. If the swaging strength is too small, it is highly likely that merely applying a relatively small tension force during a surgical operation would result in loosening out of the suture from the end of the needle. On the other hand, if the swaging strength is excessively large, there should be considered the case where the suture cannot be pulled out of the needle when a person tries to detach the needle from the suture with fingers or a needle holder after a suturing operation is completed.
In order to eliminate the above drawbacks, the swaging strength is necessary to be set within a predetermined allowable range. However, to obtain a swaging strength of a desired value, it is important to accurately position the end of the needle during a swaging step to a target position (i.e., to exactly adjust a position at which the end of the needle is swaged by the swaging device to a predetermined position).
A high technique is required to set every needle exactly in the same direction at the same position relative to the needle retaining unit. Even if the needle is directed in the correct direction before setting the needle on the needle retaining unit, the position of the needle may be displaced during an actual setting. Therefore, it is highly likely that the actual position of the end of the needle after setting may be displaced from the target setting position. This positional displacement results in producing needle attached sutures with the swaging strength varied greatly.
In view of the above, this invention is directed to a method for manufacturing needle attached sutures and an apparatus therefor, capable of precisely positioning the end of a needle held by a needle retaining unit at a predetermined position to stably obtain a desired swaging strength.